As a method for measuring body fat (subcutaneous fat, visceral fat) safely and easily, a technique utilizing measurement of biological impedance (BI) and a technique utilizing a difference between muscle and fat in light absorption rate by applying light to the human body and measuring subcutaneous fat based on the amount of reflected light are known.
For example, Patent Publication No. 3396663 (Patent document 1) discloses a body fat measuring device in which a plurality of electrodes are disposed around a waist portion of the subject and voltage generated by passing an current between specific electrodes is measured, thereby computing impedance, in turn, fat amount.
Patent Publication No. 3035791 (Patent document 2) discloses a method and a device for measuring subcutaneous fat thickness of the human body by means of light.
Unexamined Patent Publication No. 2000-350710 (Patent document 3) discloses a method and a device for computing the visceral fat by measuring the subcutaneous fat thickness using an impedance method and an ultrasonic means.
Unexamined Patent Publication No. 2003-169783 (Patent document 4) discloses a device for measuring the subcutaneous fat thickness according to an optical method.
However, in the device disclosed in Patent document 1, a total fat amount of the waist portion of the subject is measured and a visceral fat amount is estimated from a measured value on the basis of correlation between the total fat amount and the visceral fat amount. In this case, the visceral fat cannot be separated from the subcutaneous fat in the impedance measurement, and they are separated from each other according to estimation based on personal physical information (height, waist circumference, etc.). Patent document 1 also discloses another device in which electrodes for current application are disposed on front and back surfaces of the waist portion, electrodes for voltage detection are disposed on side surfaces and voltage between the electrodes is measured to compute the visceral fat amount. In this case, since the measured value greatly varies depending on the position of the electrodes for voltage detection, an error caused by variation due to individual difference among the subjects having different waist portion shapes and waist circumferences becomes larger.
The device disclosed in Patent document 2 can measure only the subcutaneous fat thickness and basically cannot measure the visceral fat amount.
In the devices disclosed in Patent documents 3, 4, the total fat amount is measured by attaching electrodes to hands and feet according to the impedance method. Thus, in both the Patent documents 3, 4, a site to be measured is not directly measured and the total fat amount is computed based on correlation. As a result, the measurement accuracy is not so satisfactory.
Moreover, in the devices for computing the total fat amount according to the impedance method, it is necessary to provide a database on the relation between the impedance measured in the state where the electrodes are attached to hands and feet and the body fat amount and the total fat amount is computed from the impedance measured at hands and feet on the basis of the database. For this reason, a complicated operation of preparing the database is required.